Sky gazers are in for a real spectacular view when planet Venus will pass across the face of the Sun on June 5 in a rare event that will be the last in our lifetime

The "Venus transit" -- the apparent crossing of our planetary neighbor in front of the Sun -- was captured from the unique perspective of NASA's Sun-observing TRACE spacecraft in 2004. Photo Credit: NASA/LMSAL

Sky gazers are in for a real spectacular view as planet Venus will pass across the face of the Sun on June 5 in a rare event that will be the last in our lifetime.

While crossing the Sun, Venus will appear as a small dot moving slowly across the sun producing a silhouette on the solar disk.

Transits of Venus are only possible during early December and early June when Venus' orbital nodes pass across the Sun. If Venus reaches inferior conjunction (when two planets lie in a line on the same side of the Sun) at this time, a transit will occur.

This transition happens once in 100 years. This year's will be the last one of the 21st century.

Venus transits appear in pairs within an eight year period between 2004 and 2012. The transition on June 5 will be the second one in the eight year period following a transition that appeared in 2004.

Venus transit in 2004 was visible over about 75 percent of the Earth and ended at sunrise over central and eastern North America. Scientists used the transition to compute the distance from the Earth to the Sun.

So far, only seven such events have occurred since the invention of the telescope (1631, 1639, 1761, 1769, 1874, 1882 and 2004). While the previous pairing occurred during the period between 1874 and 1882, the next transition will not take place until 2117 (December 11).

According to Nasa, this year's event can be observed across seven continents including Antarctica. The nearly 7-hour transit will begin at 3:09 pm Pacific Daylight Time (22:09 UT) on June 5th.

The transition should not be watched directly and some type of projection technique or a solar filter should be used to avoid a blinding glare.

Nasa TV will also broadcast the transit live from Mauna Kea, Hawaii. Officials say that this location offers the best viewing position of the entire transit. They will also give updates from Nasa centres across the country and locations from some of the 148 countries hosting viewing activities.